The present invention is related to a CDMA wireless communications system that enables push-to-talk and push-to-conference communications.
Wireless communications systems, such as cellular systems, have at least two popular formats by which bandwidth capabilities are maximized. The first is known as TDMA, or time division multiple access, and divides a frequency channel into time slots. The second is known as CDMA, or code division multiple access, which allows simultaneous broadcasts using different orthogonal codes such that a filter may use the orthogonal codes to eliminate or reduce the interference between different users.
While most cellular phone calls allow full duplex communications, some communications may be handled in a half-duplex manner, where only one party to the call is allowed to talk at a time. One example of such an arrangements is known as “Push-to-talk” functionality, where a party may both talk and listen during a call, but not both simultaneously. Such an arrangement essentially mimics the capabilities of a CB radio or walkie-talkie. TDMA systems have for several years had “push-to-talk” capabilities, as exemplified by U.S. Pat. Nos. 4,979,231 and 4,873,711. However, the push-to-talk has not been substantially available in CDMA systems, due to a number of technical difficulties.